This application is based upon and claims the benefit of the priority from the prior Japanese Patent Application No. 2000-275291, filed on Sep. 11, 2000; the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a process unit with a cleaner and an image forming apparatus comprising the same.
2. Description of the Related Art
An electrophotographic image forming apparatus which comprises a conveyor for conveying recording papers and an image forming mechanism for forming a desired image on a recording paper conveyed by the conveyor is well known. The image forming mechanism includes a rotatable photosensitive drum, a charger for charging an outer circumferential surface of the photosensitive drum, an exposure device for forming a desired electrostatic latent image on the charged outer circumferential surface of the photosensitive drum, a developing device for developing the electrostatic latent image on the outer circumferential surface of the photosensitive drum with toner to form a toner image, a transfer device for transferring the toner image formed on the outer circumferential surface of the photosensitive drum to a recording paper being conveyed by the conveyor, and a cleaner for removing toner remaining on the outer circumferential surface of the photosensitive drum after transferring the toner image from the outer circumferential surface of the photosensitive drum to the recording paper being conveyed.
In recent years, electrophotographic image forming apparatuses have been sold in which the conveyor and various devices included in the image forming mechanism are arranged for reducing an area on a floor required to place each of the image forming apparatuses thereon. In this kind of image forming apparatus, the conveyor is arranged to convey recording papers upward from the vicinity of the floor. And, this kind of image forming apparatus is called as a vertical recording-paper conveyance type image forming apparatus. In the vertical recording-paper conveyance type image forming apparatus, a conveyance path of recording papers extends from a lower end portion to an upper end portion of the apparatus, and the photosensitive drum and the transfer device of the image forming mechanism are provided in both sides of the conveyance path. Further, in the side of the conveyance path where the photosensitive drum is provided, the cleaner, the charger, the exposure device and the developing device are provided in this order around the outer circumferential surface of the photosensitive drum from an upper side of the drum to a lower side thereof. The rotation direction of the photosensitive drum is the same as the conveying direction of the recording paper on the conveyance path to which the photosensitive drum faces.
In the vertical recording-paper conveyance type image forming apparatus, therefore, the cleaner is provided in the upper side of the outer circumferential surface of the photosensitive drum, to be adjacent to the outer circumferential surface. The cleaner includes a residual toner scraping blade pressed against an upper portion of the outer circumferential surface of the photosensitive drum. Therefore, residual toner scraped off by the blade from the upper portion of the outer circumferential surface of the rotating photosensitive drum stays at the upper portion of the outer circumferential surface of the rotating photosensitive drum by the action of gravity.
The cleaner in the conventional vertical recording-paper conveyance type image forming apparatus has a paddle which rotates near the tip end of the scraping blade and a storage container for scraped residual toner. The paddle cyclically move the scraped residual toner which stays on the upper portion of the outer circumferential surface of the rotating photosensitive drum to a portion distant from the upper portion of the outer circumferential surface of the photosensitive drum in the storage container.
However, when an amount of the scraped residual toner attached on the paddle gradually increases by the use of the paddle for a long time period, a moving efficiency of the scraped residual toner by the paddle is lowered, and the amount of the scraped residual toner stayed on the upper portion of the outer circumferential surface of the photosensitive drum increases.
As a result of this, the scraped residual toner leaks from the cleaner in some cases. Further, paper particles sticking to the outer circumferential surface of the photosensitive drum from recording papers, products generated by corona discharge in a case of using corona discharge in the charger and/or transfer device and sticking to the outer circumferential surface of the photosensitive drum, and any other objects sticking to the outer circumferential surface of the photosensitive drum, together with the scraped residual toner, are also scraped off from the outer circumferential surface of the photosensitive drum by the blade and stay on the upper portion of the outer circumferential surface of the photosensitive drum.
In order to prevent the above described moving efficiency from lowering, it has been also performed that a free end of a scraper is made in contact with a surface of the paddle at a position apart from the upper portion of the outer circumferential surface of the photosensitive drum. The free end of the scraper being in contact with the surface of the paddle scrapes the scraped residual toner attached to the surface of the paddle from the surface of the paddle. The scraped residual toner scraped from the surface of the paddle at the above described apart position is discharged to an outside of the cleaner by well known discharging means.
The scraper making in the sliding contact with the surface of the paddle, however, not only generates noise by the above described sliding contact, but also abrades the free end of the scraper and the surface of the paddle. The abrasion of the surface of the paddle causes a lowering of the above-described moving efficiency.
The present invention has been derived from the above-described circumstances, an object of the present invention is to provide a process unit with a cleaner, including a blade which scrapes residual toner from an upper portion of an outer circumferential surface of a photosensitive drum, and a paddle which feed cyclically scraped residual toner to a position distant from the upper portion of the outer circumferential surface of the photosensitive drum, the process unit with a cleaner being capable of efficiently feeding the scraped residual toner from the upper portion of the outer circumferential surface of the photosensitive drum to the above-described position distant from the upper portion for a long period, capable of reducing an amount of the scraped residual toner stayed on the upper portion of the outer circumferential surface of the photosensitive drum, and further capable of reducing noise occurring with an operation of the process unit with a cleaner.
Moreover, an object of the present invention is to provide an image forming apparatus comprising the process unit with a cleaner as described above.
In order to achieve the object of the present invention as described above, a process unit with a cleaner, according to the present invention, comprises:
a photosensitive drum which is rotatable and has an outer circumferential surface on which toner is to be sticked; and
a cleaner which removes toner sticking on the outer circumferential surface of the photosensitive drum,
the cleaner including
a blade which scrapes the toner sticking on the outer circumferential surface of the photosensitive drum from the outer circumferential surface,
a paddle which has a rotation center and at least one arm projecting outward from the rotation center in a radial direction of the rotation center, rotates in a predetermined direction at a position near a toner scraping position by the blade on the outer circumferential surface of the photosensitive drum, and moves cyclically the scraped toner scraped from the outer circumferential surface of the photosensitive drum by the blade, from the toner scraping position, and
a scraper which is provided in a side of the paddle opposite to the outer circumferential surface of the photosensitive drum and has a free end disposed radially outwardly and near to a rotation locus drawn by a radially directional outer end of the arm of the paddle during a rotation of the paddle, the free end scraping the scraped toner carried by the arm of the paddle rotated to the opposite side during the rotation of the paddle.
In order to achieve the object of the present invention as described above, an image forming apparatus according to the present invention, comprises:
a conveyor which conveys a recording paper;
a photosensitive drum which rotates in a predetermined direction;
a charger which charges an outer circumferential surface of the photosensitive drum;
an exposure device which forms a desired electrostatic latent image on the charged outer circumferential surface of the photosensitive drum;
a developing device which develops the electrostatic latent image by toner and forms a toner image;
a transfer device which transfers the toner image formed on the outer circumferential surface of the photosensitive drum, to the recording paper being conveyed by the conveyor; and
a cleaner which removes the toner sticking on the outer circumferential surface of the photosensitive drum, after transferring the toner image from the outer circumferential surface of the photosensitive drum to the recording paper being conveyed by the conveyor,
the cleaner being provided adjacent to the outer circumferential surface of the photosensitive drum, and
the cleaner including:
a blade which scrapes the toner sticking on the outer circumferential surface of the photosensitive drum from the outer circumferential surface;
a paddle which has a rotation center and at least one arm projecting outward from the rotation center in a radial direction of the rotation center, rotates in a predetermined direction at a position near a toner scraping position by the blade on the outer circumferential surface of the photosensitive drum, and moves cyclically the scraped toner scraped from the outer circumferential surface of the photosensitive drum by the blade, from the toner scraping position; and
a scraper which is provided in a side of the paddle opposite to the outer circumferential surface of the photosensitive drum, and has a free end disposed radially outwardly and near to a rotation locus drawn by a radially directional outer end of the arm of the paddle during a rotation of the paddle, the free end scraping the scraped toner carried by the arm of the paddle rotated to the opposite side during the rotation of the paddle.